Traditional wood lining, with kerfing. I use special epoxy specifically designed to bond with aluminum. I use aluminum angle, 1/16" x 1/2" x 1/2" for bracing on the top (bonded with epoxy). Bridge is bolted to the bracing through the top, for strength (top does not buckle or bow, etc.) Most any tuning can be used, with no concern for damage to the guitar, as is the case with most wood Weissenborn lap steel guitars.